1. Field of the Invention
The present invention relates to a sheet treating apparatus for applying a treatment to a sheet and an image forming apparatus provided with the same. In particular, the present invention relates to a sheet treating apparatus which is capable of performing full load detection at low costs by effectively using full load detecting means for detecting full load with a flag in treating a sheet and an image forming apparatus provided with the same.
2. Related Background Art
Up to now, for example, in order to reduce time and labor required for treatments such as alignment and stitch with respect to a sheet such as a copy sheet having images formed thereon, some of image forming apparatuses such as a copying machine, a printer, and a facsimile machine, are each provided with a sheet treating apparatus adapted to take the sheets having images formed thereon into the apparatus one after another and apply treatments such as alignment and stitch to the sheets.
Here, such a sheet treating apparatus is an apparatus which is capable of performing a treatment in a plurality of modes such as a mode for simply delivering sheets to a sheet stacking portion and stacking the sheets thereon and a mode for delivering sheets to a sheet stacking portion and stacking the sheets thereon after applying alignment and stitch treatments to the sheets in an intermediate stacking portion or the like. These sheets are stacked on an identical stacking portion. The sheet treating apparatus often detects full load of sheets on the sheet stacking portion using a transmissive photosensor or the like.
However, in the case in which a transmissive photosensor is used for detecting full load of sheets on a sheet stacking portion as in the above-mentioned conventional example, there is a problem in that the transmissive photosensor is costly.
Thus, some of the conventional sheet treating apparatuses detect full load of sheets on a sheet stacking portion according to a full load detecting flag provided with a pivotal fulcrum above a pair of delivery rollers for delivering sheets to the sheet stacking portion. In such a sheet treating apparatus, cost reduction can be realized by using the full load detecting flag.
However, the full load detecting flag is arranged among a plurality of intermediate stacking portions for temporarily holding sheets in order to perform treatments such as alignment and stitch and is provided with the pivotal fulcrum above the pair of delivery rollers as described above. Therefore, unless the full load detecting flag is retracted from a sheet transport path to the intermediate stacking portion, the full load detecting flag is pushed up by a sheet when the sheet is delivered. The pushed-up full load detecting flag abuts against the intermediate stacking portion and cannot pivot, whereby sheet jam occurs. In addition, when the full load detecting flag is lifted once, the intermediate stacking portion is placed above the sheet stacking portion, and, for example, the full load detecting flag is lifted upward for a predetermined time by sheets at the time of sheet alignment. Thus, the full load detecting flag detects an alignment surface during the alignment to erroneously detect that the sheets are fully loaded.
Therefore, the present invention has been devised in view of such a present situation, and it is an object of the present invention to make it possible to detect full load at low costs by effectively using full load detecting means for detecting full load with a flag.
In order to attain the above-mentioned object, a representative structure of the present invention is a sheet treating apparatus for applying treatments to a sheet delivered from an image forming apparatus main body, which includes: a first intermediate stacking portion for hitting an edge of a sheet in a transport direction of the sheet against a wall to align the sheet; delivery means for delivering a sheet from the first intermediate stacking portion; a second intermediate stacking portion provided with a function for carrying-in and supporting a sheet downstream of the delivery means in the transport direction and aligning edges of the sheet in a cross direction perpendicular to the transport direction of the sheet; a sheet stacking portion located in a lower position in the gravitational direction of the second intermediate stacking portion; and full load detecting means for detecting full load of sheets on the sheet stacking portion, in which the full load detecting means is means for contact-detecting a height of an upper surface of sheets on the sheet stacking portion with a full load detecting flag, which has a pivotal fulcrum in a higher position than that of the delivery means, and does not perform full load detection of sheets at the time of a sheet treatment in the intermediate stacking portion.
According to the above-mentioned structure, since full load detection of sheets is not performed at the time of a sheet treatment in the intermediate stacking portion, it is possible to perform full load detection of sheets effectively using the low-cost full load detecting means with the full load detecting flag.